Harbinger transposons and an ancient HARBI1 gene derived from a transposase
Harbinger transposons and an ancient HARBI1 gene derived from a transposase
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DOI：
10.1089/104454904323090949
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发表时间：
2004-05-01
影响因子：
3.1
通讯作者：
Jurka, J
中科院分区：
文献类型：
--
作者：
Kapitonov, VV;Jurka, J
在本研究中，我们报道了在原生生物、植物、昆虫、蠕虫和脊椎动物中发现的Harbinger DNA转座子的主要特性。这是真核生物DNA转座子的第一个超家族，其中所有自主转座子，即使是来自不同物种的转座子，都编码两种蛋白质：超家族特异性转座酶和DNA结合蛋白，其特征是存在保守的SANT/myb/三螺旋基序。已知最后一个基序对于不同转录调节因子的DNA结合是重要的。因此，我们认为该蛋白是Harbinger转座酶协调表达所必需的。尽管哺乳动物基因组中没有可识别的Harbinger残体，但我们发现了一个广泛表达的HARBI1基因，该基因编码一个350-aa蛋白，完全来自约4.5 -5亿年前的Harbinger转座酶。HARBI1蛋白在人类、大鼠、小鼠、奶牛、猪、鸡、青蛙和各种硬骨鱼中都是保守的，其他极其重要的蛋白包括RAG1和RAG2。在Harbinger转座中检测到的保守基序在HARBI1蛋白中也得到了很好的保存。因此，HARBI1蛋白有望成为骨性脊椎动物功能的重要核酸酶。我们还发现，与HARBI1最相似的蛋白质是由一个自主的Harbinger 3-DR转座子编码的，该转座子在几百万年前在斑马鱼基因组中具有转座活性。从Harbinger3_DR衍生的非自主转座子的特点是对先前在任何其他DNA转座子中从未见过的17 bp靶位的显著偏好。基于这一观察，我们认为假设的HARBI1核酸酶也具有很强的dna靶向特异性。
In this study we report main properties of Harbinger DNA transposons identified in protists, plants, insects, worms, and vertebrates. This is the first superfamily of eukaryotic DNA transposons where all autonomous transposons, even those that are hosted by species from different kingdoms, encode two proteins: a superfamily-specific transposase and a DNA-binding protein characterized by the presence of the conserved SANT/myb/trihelix motif. The last motif is known to be important for the DNA binding by different transcription regulators. Therefore, we suggest that this protein is necessary for coordinated expression of the Harbinger transposase. Although mammalian genomes are free of recognizable remnants of Harbingers, we identified a widely expressed HARBI1 gene encoding a 350-aa protein entirely derived from a Harbinger transposase some 450-500 million years ago. The HARBI1 proteins are conserved in humans, rats, mice, cows, pigs, chickens, frogs, and various bony fish, as well as other extremely important proteins, including RAG1 and RAG2. Conserved motifs detected in the Harbinger transposases are also well preserved in the HARBI1 proteins. Therefore, the HARBI1 proteins are expected to be nucleases important for functioning of bony vertebrates. We also found that the protein most similar to HARBI1 is encoded by an autonomous Harbinger 3-DR transposon that was transpositionally active in the zebrafish genome a few million years ago. Nonautonomous transposons derived from Harbinger3_DR are characterized by a striking preference for a 17-bp target site never seen previously in any other DNA transposon. Based on this observation, we suggest that the hypothetical HARBI1 nucleases are also characterized by a strong DNA-target specificity.